New year's omochi after (osonae & kagamibiraki)

What is cutting a Kagamimochi?
鏡開きって何？

I want the offerings of God and Buddha year the New Year.
Was on January 11, to give thanks to God and Buddha year,
I eat with my family that mochi.
仏様や年神様の為に、お餅をお供えします。
仏様や年神様に感謝し、1月11日に
鏡開きをしてそのお餅を家族で食べます。